1. Technical Field of Invention
This invention relates to floating waterfowl decoys, specifically to self-propelled decoys which imitate the swimming and splashing motions of live waterfowl.
2. Description of Prior Art
Floating waterfowl decoys are used in the hunting of ducks and geese to attract waterfowl into the hunting area. Though the appearance of these decoys is quite lifelike, on calm days they do not provide the attraction that live, moving ducks would. Many animated decoy models have been built to address this problem of stationary decoys, and all have substantial drawbacks.
Decoys which produce ripples and some slight movement in the water have been animated by battery-powered vibrators or air pumps. These models improve on the completely motionless decoy, but are still not lifelike, as they do not swim or change the configuration of the decoy set, nor do they create v-shaped wakes in the water in the manner of a live waterfowl. They also have operational problems. All battery-powered motors in floating decoys present difficulties with changing batteries in cold, dark conditions, corrosion of contacts, poor battery performance in low temperatures and cost of replacement batteries. Air pump models are tethered to the shore by their air lines and require constant attention of the hunter (whom they occasionally trip!) in their operation.
Several swimming decoys have been invented. These imitate a living duck much more closely, providing good attraction on calm days when there is no other motion in the decoy set. Their drawbacks are largely functional. These models have various methods of propulsion power, each with its own difficulties.
Propeller-driven models can provide lifelike movement, but are prone to the same battery problems as mentioned above, and are often entangled in the weeds of the shallow, marshy hunting ponds where they are used. In order to be lightweight enough to get substantial operating time from a set of batteries, the drive apparatus must be of light, fragile construction and often these models are not durable in the difficult conditions of decoy bags, boats and backpacks where they are stored and carried.
Some swimming models have used a battery powered water jet for propulsion. These have the same battery-related problems previously mentioned, and frequently suffer plugged intake ports from mud and plant matter in the swampy water in which they operate. In order to be effective, a moving decoy needs to operate trouble-free independent from the hunter for extended periods of time.
Several recent inventions in this field have featured moving wings or feet or both. Though these motions are not very lifelike, wing-flapping and foot splashing can be effective in attracting flying birds at long distances. The apparatus tends to repel birds at the closer distances of xe2x80x9cshooting range,xe2x80x9d especially after the batteries pass their peak of power and the motion starts slowing down. The mechanisms by which they move are complex, require substantial assembly by the hunter, and are much too delicate for field conditions. The cost of flapping and kicking decoys is beyond many hunters, and they do not hold up well in actual use.
Radio controlled models are too delicate and expensive for practical use, and many of the mechanical difficulties discussed above may apply, depending on the method of propulsion.
The main problems found in researching moving, floating waterfowl decoys were: fragility, need for substantial hunter field assembly and attention, plugging and entangling of parts, battery problems of expense, inconvenience and corrosion, and expense to produce the decoy.
One of the best attempts to solve these difficulties is the decoy by Sumrall, U.S. Pat. No. 5,775,027, which uses a detachable base to house the apparatus for a sculling propeller. The sculling blade or fin of this decoy does protrude outside the base of the decoy, however, and is still quite prone to entanglements. The base and decoy body must still be assembled by the hunter in the cold, dark pre-hunt conditions, as it is not sturdy enough to survive long in a decoy bag full of wet, jostling decoys and weighted lines. The design is quite complex, and the resulting commercial product is expensive, out of the price range of many duck hunters. Battery problems are also inherent in this model.
This decoy system is unique over prior art in its simplicity of design and operation. There are no moving parts to break, no mechanical joints or bearing surfaces, and no mechanical connections to wear or jam. It is powered by inexpensive fuel rather than electricity and so avoids problems of corrosion of electrical connections, stabilization of heavy batteries and high replacement costs of batteries. The decoy system is of single-unit construction and requires no assembly to put into use. This is crucial under the cold, dark conditions of waterfowl hunting. It has no mechanical protrusions beyond the outer surface of the decoy to break off when stored in a decoy bag. The smooth, moderate motion produced by the jet motor is characteristic of the natural gliding movement for which duck, geese and swans are famous. Jerky, circular motions and splashing and spurting are also characteristic of such waterfowl. This moving decoy can be produced by modifying existing hollow shell floating decoys or manufactured directly with minimum modifications to an existing production decoy shell. Its apparatus is simple, low cost and easily assembled, and so the retail product will be inexpensive to produce. The simplicity of the design also improves durability, since, with no moving parts or joints in the propulsion assembly, there is nothing to bend, break or fail. Numerous advantages over prior art are realized by utilization of a pulsating steam boiler to propel a waterfowl decoy. These advantages are inherent in the very nature of the propulsion system. A drop of water converted by heat to steam displaces approximately 1700 times the volume of the original drop of water. The pulsating steam boiler consists of two tubes starting just below water level and extending into a boiler chamber where heat is applied. When heated, the boiler chamber expands, causing pressure gradient that pulls water into the boiler chamber. Water reaching the hot boiler xe2x80x9cflashesxe2x80x9d into steam, expands tremendously and forces a jet of water out of the tubes, at the same time cooling the metal and the water vapor within the tubes, which draws another charge of water into the chamber to repeat the cycle. This process results in a net forward thrust, as a relatively low velocity intake of water is coupled with a much more vigorous jet thrust or exhaust.
The inherent characteristics of this propulsion method solve a host of problems experienced in prior art. Since it requires no drive axles, no moving parts with bearing surfaces (above or below water line) and tends to clear potential clogging of the jet tubes as it cycles, it avoids many of the operational and attraction problems of moving decoys to date. Needless to say, the difficulties associated with battery use are not an issue. None of the parts of this propulsion system are particularly corrosion. No delicate moving parts means no field assembly by the hunter and fewer potential breakdown points.
Wrapping of weeds around protruding propellers or jet units does not happen, since there are no substantial protrusions from the decoy shell below the water line. The decoy may be carried in a decoy bag with other decoys without special protections, as it has no external parts to snap off or bend.
Since there are no protrusions beyond the decoy other than an unobtrusive vent on the top of the decoy, appearance at close range is natural. The natural, gliding movement of ducks, geese and swan is duplicated precisely by the head-up swimming decoy. The jerky, circular motion of the head-down, feeder decoy also very closely resembles the natural feeding motion of waterfowl. Since all appearance and motions are realistic, waterfowl are at no point repelled by the decoy and will join it as one of their own, even after landing.
The simplicity of this propulsion system allows for an uncomplicated modification of an existing decoy shell, which should result in low-cost production. Components are inexpensive and easy to assemble. This decoy will be retailed at the lower end of current market prices for moving decoys.
A mechanism which propels a floating waterfowl decoy and the modifications to a decoy shell which make installation and operation of that mechanism possible. Propulsion is produced by a steam jet motor which requires no moving parts other than metal expansion and contraction. The mechanism can be installed in virtually any rigid to semi-rigid hollow to semi-hollow floating waterfowl decoy. The preferred embodiment is a swimming upright decoy, with a feeding waterfowl decoy, such as a duck, as another embodiment.